Assume that the total cost function of a firm () with no fixed cost (i.e intercept is zero) and diseconomies of scale is approximated by the quadratic function , where  is the number of units produced and  is an error term. Obtain the formula of the Ordinary Least Square estimator of β_1. 

OLS equation

Assume that the total cost function of a firm () with no fixed cost (i.e intercept is zero) and diseconomies of scale is approximated by the quadratic function , where  is the number of units produced and  is an error term.

Obtain the formula of the Ordinary Least Square estimator of β_1.